Investments - Summary of the Levels of the Fair Value Hierarchy into Which the Company's Financial Assets Fall (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Fair value measurements
Total financial assets	$ 168,170	$ 270,301
U.S. Treasury Instruments
Fair value measurements
Cash and cash equivalents	15,000	62,949
Investments in securities	100,767	173,960
Level 1
Fair value measurements
Total financial assets	1,177	327
Level 2
Fair value measurements
Total financial assets	166,993	269,974
Level 2 \| U.S. Treasury Instruments
Fair value measurements
Cash and cash equivalents	15,000	62,949
Investments in securities	100,767	173,960
Government Securities Money Market
Fair value measurements
Cash and cash equivalents	51,226	33,065
Government Securities Money Market \| Level 2
Fair value measurements
Cash and cash equivalents	51,226	33,065
Common Stock
Fair value measurements
Investments in securities	1,177	327
Common Stock \| Level 1
Fair value measurements
Investments in securities	$ 1,177	$ 327

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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